I'm still suspecting the AFR was measured with the front wheels stationary - The OP isn't used to working with constant depression carbs.  It's an easily overlooked principle, so it'll be interesting to hear back from him.

I think the smog gear injected air into the exhaust ports NOT into the combustion chamber.

Typical HS4:

The "Canadian" Minis with anti-smog gear had a belt-driven pump that pushed air into the combustion chambers exhauts ports (?) (I don't know how they were regulated or a what rpm or load etc.) but removing the pump and banking off the ports would tend to richen the exhaust mixture. At higher rpm, theoretically it would push more air into the chambers. Since you don't have the pump, I think your engine would tend to run richer at higher rpm.

Yes, to what Malsal and Jeg said about the ports. They look like unused bolt holes but are really vents.

The dashpot spring I was referring to is not the tiny spring behind the needle (as shown in jeg's picture) but much larger and hidden between the dashpot dome and piston. Here's a picture of the two main sizes of springs and a HIF44 carb on the same paper towel for size comparison.  (I'm not sure if you were checking the right spring.)

 

Is the hose from the valve cover to the carb direcly into the carb, or does it have a pcv valve fitted?  Which cap is fitted to the valve cover and is the breather on the tappet cover blanked off or plumbed into the valve cover or perhaps 'Y' connected to the carb as well? 

Try unplugging the carb from the CV system and cap the port on the carb - see what happens.

Yeah, sometimes it's discovered that the gasket between the air filter elbow and carb body is installed upside down, thereby blocking the holes.

I need to ask you if your wideband is measuring this 14 - 18 AFR while the vehicle is stationary sitting in the garage or is the engine pulling a load (rolling road dyno or driving down the street)? 

If it's just sitting in the middle of your garage floor and you rev it up, the SU carb will run lean relative to rpms because there's virtually no work being done - just spinning faster; remember, the SU is a variable venturi carb.  (no, - not a slide carb - ) 

Make sure the needle sits flush to the bottom of the piston - I use a 6" stainless scale laid flat across the piston such that the shoulder rests on the edge of the scale.  Ensure that the carb oil is topped off to around 1" below the top of the hollow piston rod and damper the damper is fitted/screwed down.

If you were to support the lower ball joints/lower arms such that the tires are off the ground and the driveshafts are parallel to the ground, with a wheel or 2 under the doorsills to support the body in the event that it should come crashing down, you can simulate the driving experience by careful use an assistant and of the brakes.  Take care not to overheat them.

This is a reprint of an article that David Vizard wrote long ago:  Vizard:  Mixing it on Your Own Dyno

BTW - I checked Berlen Fuel Systems website for the FZX 1150 carb - Canadian mini 1000 showing the std. needle as ADD. 

Service Replacement Spare Parts w/diagram ('Full Spares List' link to the FZX 1150 std. service replacement FZX 3013)

 

If the air filter has been replaced with a K&N (or other non-standard paper filter), or the exhaust has been changed to an RC40 (for example), or it's got an alloy intake manifold (or steel tubular)/extractor-type exhaust manifold, then this standard ADD needle probably won't work.  If the vehicle still has the cast intake/exhaust manifold & peashooter exhaust, paper filter, it'll be fine.  If it's been changed, take pictures or tell us what it's got and we can try to steer you towards something suitable.

I don't know if you checked this already, but if the vehicle sat around for a while, it could be something as simple as a fuel filter or debris in the carb float chamber - remove the cover from the float chamber, siphon the fuel out, remove the suction chamber assembly from the carb body, use a bit o'hose to seal against the jet - blow through the other end of the hose (not 120psi from the compressor, the mouth works well for this) and see if it's clean through to the float chamber. 

Hope this helps -

Oh, another thing - "or the motor is not a 998cc (larger) so it needs a larger needle."  -  not necessarily the case.  Many small bore engines use needles that would gag larger bores.  It's all about air speed over the jet...

i am worried about that smog stuff....long time ago when i was working on american cars with carbs in the lat 80's i found out the hard way that the smog stuff sometimes imposes metered air leaks thus affecting the required jetting so by hijacking the smog (ie toss it in the neighbour pool) was making the cars go worse.

noteworthy the last american carbureted ford escorts (1989?)with 10 km of vacuums tubing and solenoids.

 

even my BMW 1974 2002 (actual daily driver) used to have such scrap that was affecting a lot the required jetting that once removed the car was working like crap on a solex 32/32 carb.

given the charts and comprisions, there is no specific answer as to what would be a proper "richer" needle on a waxstat carb, starting from a ADD one...the AAA seems to be a bit too agressive imho....but worth a try.

 

i found mintylamb already, hence the asking for the AAA needle...

 

would it be faire to say that the ADD needle was "right" for the period with the smog stuff ?

there was some stuff removed that i cant tell, only thing that remains is the cranckase system that is at last a closed system where the carb sucks the air from the valve cover. no leak there either.

The air vents i think Dan is referring to are the ones (2) facing the air filter just above the air filter mounting bolts.

Try Mintylamb.co.uk for needle selection and comparisons then Joecurto.com for needles.

Make sure the didstributor is advancing correctly sometimes the weights sieze, no more than 34 degrees max.

i went all over the carb and the theory behind the waxstat and whats not.

that carb is like new.

the waxstat alone doesnt explain why it runs uber rich at idle and lean at higher revs. to me it looks like it would affect the whole rpm/mixture range, not just a part of the rpm/vacuum.

all gaskets are new, flatened surfaces, no leak anywhere.

its an ADD with a 0.090 no doubt.

i do have proper SU oil in the damper. the spring is not realy identifiable, i dont see any paint mark on it (??)

the piston can move all the way up with some "restriction" because of the oil in the damper.

there is no blocked passages from the air filter side to the underside of the piston.

holes in the damper piston are to the side engine, all is correct....how one could put the piston backward anyway since there is an index key ??

i can only see two problem, lack of vacuum for wathever reason, or the motor is not a 998cc (larger) so it needs a larger needle.

i would realy like to put my hands on a AAA needle....

i can make the car "runs" semi correct, an unatended user/owner wouldnt be able to realy tell, it just lack power and i see the AFR so I know.

thanks for any more helps/ideas.

Waxstats are supposed to fail to a rich condition.  They provide a richer mixture at cold and as the engine warms, the wax expands, leans out the mixture. Failure of the wax should leave a rich condition - the jet doesn't move up. If you were to tune an already failed waxstat, I think it would act like a regular non-waxstat, and the needle's specs would be OK.

Is the carb dashpot spring still in place? Is it the right one?

Are the air vents open at the face of the carb flange on the air filter side?

Either of these will affect the function of the dashpot and mixture. If the dashpot rises too soon or too much it could lead to a lean condition at higher rpms. The dashpot does two things at the same time: it regulates the fuel flow by pulling the needle out AND regulates the air flow across the bridge. The air flow directly over the tip of the jet is what pulls fuel up. The bottom end of the piston regulates the air flowing through the throat of the carb - in relation the amount of fuel IF the spring rate and vacuum pull are in correct proportion.

The air vents at the filter end of the carb body provide relief venting - if they are covered the carb may not work properly.

The "accellerator pump' action of the dashpot works by the oild damper delaying the rise of the piston, keeping the thoat from opening. since the throttle is open, the draught of the engine pulls the needed air faster across the bridge and end of the jet, pulling extra fuel out, giving a "shot" of fuel for the rpm tansition. If the oil is too thin or hasn't been topped up, the dashpot opens too quickly leaving a momentary lean condition and the usual stumble.

If the dashpot spring is too weak or missing, the dashpot may rise all the way up, allowing so much air past the bridge the siphon effect is nadequate, producing a lean condition.

 

I am not sure where i seen it but there is a way to convert the waxstat to a regular jet by taking it apart and putting a penny spacer in the bottom.

Hopefully someone may offer up a non waxstat carb for less than that conversion costs.

That would be an ADD needle.  It's what seems to be in many Canadian cars of that era...that and ADP.
I did recently find one with a DZ ( zed ) , never come across one before

Also...check out the parts for sale

//www.minimania.com/Cars4Sale_List.cfm?adType=Part

 

You can buy a non waxstat jet with a conversion bracket.

//www.minimania.com/part/CSK65A/Hs4-Carb-Conversion-Kit--Upgrade-For-Waxstat-Style

try a needle for a slightly hopped up mini

//www.minimania.com/SU_Carbs_-_Quick_reference_needle_selection

You can make a richer needle out of that old ADD item.

keep in mind the ADD was for a stock 998 with leaded fuel from the seventies, on an engine with an air injection pump type emissions system. The many minis still functioning with that thing are a direct result of the fact that 998s just don't care too much.

is there a way to tamper with the waxstat other than making a non-waxstat conversion ?

sounds like the source of the problem...

 

thanks.

there is no vacuum leaks, first thing i checked.

the evap is closed end to end, no air leaks there either.

 

problems truly started after the guy sent it to be rebuilded by a "reputed" shop in Mtl (im in sherbrooke). the car never ran like before, everything beign relative of course as i never tried the car before.

 

i am not a novice. i regularly play with delortos, webers and solexes on other brands, only on older cars BUT rarely on SU, i am honnest there.

 

seems to be a ADD in there but the carb realy leans out at high revs no matter what.

there is indeed a waxstat. i am on my way to crack it open as its the only things left to break on this poor car.

what would you suggest.

thanks.

Probably an ADD as that was the common item.

does the carb have a waxstat? Type jet? grief!

are there vacuum leaks? Grief!

is the pcv and evaporative emissions system connected from one end to the other?

Does the butterfly still have a valve in it?

where are you?

Hi, i need to fix a 1977 mini 1000 for a friend.

i have some problems to identify the needle in the carb, it is A0D or ADD, i cant tell, the stamping is almost impossible to read.

The main issue is that the engine runs lean as the rpm rises. the guy had the carb rebuilded somewhere else and it came back with this issue.

What needle should be in there ?

 

i am extremely well equiped, i have wide band 02 sensor connected to the car so i can tell the afr to trouble shoot the issue.

idle: 10:1 afr

mid rpm and up, 14-18 afr.

i seriously think the guy put back in a wrong needle from another carb, lets say, a dual carb set-up....

carb is a FZX1150, motor is stock. no air leaks, no mechanical problems identified.

thanks for any helps.